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1. (WO2018044821) RÉDUCTION DE LA TENEUR EN MONOMÈRES RÉSIDUELS DANS DES COPOLYMÈRES DE STYRÈNE ET DE VINYLPYRIDINE
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS

What is claimed is:

1 . A process for preparing a copolymer of styrene and a vinylpyridine having a

residual monomer content of less than about 1000 parts per billion (ppb), the process comprising:

a) mixing styrene and vinylpyridine monomers, an aqueous solvent, an alkalizing agent, and a surfactant to form an emulsion;

b) heating the emulsion at a temperature of about 50°C to about 60°C in the presence of a polymerization initiator to form the styrene-vinylpyridine copolymer;

c) contacting the emulsion from step (b) with sodium hydrogen phosphate to form a coagulated copolymer; and

d) isolating and drying the coagulated copolymer at a temperature of at least about 60°C under reduced pressure or an inert atmosphere to produce the copolymer of styrene and a vinylpyridine in which the residual monomer content is less than about 1000 ppb.

2. The process of claim 1 , wherein, at step (a), the aqueous solvent is water, the alkalizing agent is a hydroxide salt, and the surfactant is a salt of oleic or lauric acid,

3. The process of claims 1 or 2, wherein the polymerization initiator at step (b) is sodium persulfate.

4. The process of any one of claims 1 to 3, wherein sodium hydrogen phosphate at step (c) is an aqueous solution of sodium hydrogen phosphate.

5. The process of claim 4, wherein the emulsion from step (b) is heated to a

temperature from about 50°C to about 55°C before contact with the aqueous solution of sodium hydrogen phosphate.

6. The process of claim 5, further comprising heating to a temperature from about 50°C to about 55°C for at least one hour after contact with the aqueous solution of sodium hydrogen phosphate.

7. The process of any one of claims 1 to 6, wherein the temperature of drying at step (d) is from about 70°C to about 80°C.

8. The process of any one of claims 1 to 7, wherein the drying at step (d) occurs at a pressure from about -6.77 x 104 Pa to about -1 .02 x 105 Pa or under a nitrogen, argon, or helium atmosphere, and the drying at step (d) proceeds for at least 24 hours.

9. A process for preparing a copolymer of styrene and a vinylpyridine having a

residual monomer content of less than about 1000 parts per billion (ppb), the process comprising:

a) adding styrene and vinylpyridine monomers to a mixture comprising an aqueous solvent, an alkalizing agent, a surfactant, and a suspending agent to form a suspension;

b) heating the suspension at a temperature of about 50°C to about 80°C in the presence of a free radical initiator to form the styrene-vinylpyridine copolymer; and

c) isolating and drying the styrene-vinylpyridine copolymer at a temperature of at least about 60°C under reduced pressure or an inert atmosphere to produce the copolymer of styrene and a vinylpyridine in which the residual monomer content is less than about 1000 ppb.

10. The process of claim 9, wherein, at step (a), the aqueous solvent is water, the alkalizing agent is a hydroxide salt, the surfactant is a salt of oleic or lauric acid, and the suspending agent is carboxymethyl methyl cellulose.

1 1 . The process of claims 9 or 10, wherein the free radical initiator at step (b) is t- butyl peroctoate or t-butyl perbenzoate.

12. The process of any one of claims 9 to 1 1 , further comprising adding a plasticizing solvent to the suspension before, during, or after step (b), wherein the

plasticizing solvent is toluene, octane, cyclohexane, heptane, benzyl alcohol, or isoamyl alcohol.

13. The process of any one of claims 9 to 12, wherein the temperature of drying at step (c) is from about 70°C to about 80°C.

14. The process of any one of claims 9 to 13, wherein the drying at step (c) occurs at a pressure from about -6.77 x 104 Pa to about -1 .02 x 105 Pa or under a nitrogen, argon, or helium atmosphere, and the drying at step (c) proceeds for at least 24 hours.

15. The process of any one of claims 1 to 14, wherein the vinylpyridine is 2- vinylpyridine, 3-vinylpyridine, or 4-vinylpyridine.

16. The process of any one of claims 1 to 15, wherein the residual monomer content is less than about 500 ppb, less than about 200 ppb, or less than about 100 ppb.

17. The process of any one of claims 1 to 16, wherein the copolymer is prepared in a batch of at least about 1 kg, at least about 10 kg, at least about 100 kg, or at least about 1 ,000 kg.

18. The process of any one of claims 1 to 17, wherein the copolymer has an inherent viscosity of about 1 .0 to about 1 .6 dL/g when the inherent viscosity is measured in a 0.25% solution of the copolymer in dimethylformamide at room temperature.

19. A copolymer of styrene and a vinylpyridine prepared by the process of any one of claims 1 to 18.

20. The copolymer of claim 19, wherein the vinylpyridine is 2-vinylpyridine, the

monomer content is less than about 200 ppb, and a 0.25% solution of the

copolymer in dimethylformamide has an inherent viscosity of about 1.2 to about 1 .4 dL/g at room temperature.